1. Field of the Invention
The present invention relates to a starting clutch mainly used in an automatic transmission of a vehicle and the like.
2. Related Background Art
FIG. 25 is an axial sectional view of a conventional starting clutch, showing an example of a conventional arrangement. A starting clutch 201 includes a wet type multi-plate clutch 203 and a damper 204 which are disposed within a case 210. In the wet type multi-plate clutch 203, friction plates 290 spline-fitted onto an outer periphery of a hub 280 and separator plates 300 spline-fitted into an inner periphery of a clutch case 310 are alternately arranged and dislodgment of these plates is prevented by a snap ring 212 disposed at an open end of the clutch case 310.
On the other hand, a piston 230 for applying a load to the friction plates 290 and the separator plates 300 is also disposed at the open end of the clutch case 310. The piston 230 is operated by supplying hydraulic oil into an oil chamber 250 defined between the piston and an inner wall of the clutch case 310, and the hydraulic oil is supplied through oil passages 271, 272 provided in members disposed at the inner peripheral side of the wet type multi-plate clutch 203 and oil passages 241, 243 provided in a drive shaft 240. Lubrication of the starting clutch is effected by an electrical pump or an engine pump mainly used for operating the piston.
While the operation of the piston of the wet type multi-plate clutch of the starting clutch has been effected by the hydraulic oil as mentioned above, in recent years, use of an electric motor or an electrically operated equipment such as a ball screw has been investigated in order to enhance accuracy of control of the operation of the piston. On the other hand, since it is not required that the hydraulic oil for operating the piston be supplied, it is considered that the electrical pump or the engine pump can be omitted, but, alternatively, it is required that means for supplying lubricating oil to the wet type multi-plate clutch be reserved.